Zur Haltung von Dallschafen (Ovis dalli) im Zoologischen Garten Leipzig: Keeping Dall's Sheep (Ovis dalli) at Leipzig Zoo

Keeping and breeding Dall's Sheep (Ovis dalli) in Leipzig Zoo between 1982 and 2009 are reflected and analysed. Seven animals were brought into the collection. 60 specimens were kept so far. The species hast turned out to be difficult in Middle-Europe‘s climate but nevertheless is manageable and reproductive. The rearing rate (animals have reached at least the age of 1 year) is 40%. Remarkable veterinarian treatments for keeping the stock healthy and especially for ensuring the breeding are described. For sure, deep engagement of keepers, veterinarians and curators is needed to keep this species successfully. Hopefully a lot of colleagues will take this as a challenge to increase numbers in Europe by joining the group of holders of this splendid wild sheep.     

Notes on the induced reproduction and development of the tigerfish,Hydrocynus vittatus (Characidae), embryos and larvae

Synopsis In South Africa, the distributional range of tigerfish,Hydrocynus vittatus, has diminished over the past fifty years mainly as a result of migration barriers and reduced river flow. A project to restock traditional tigerfish waters has been envisaged for many years but did not materialise due to an inability to spawn this species artificially. Several hormones were therefore tested for their potency to induce ovulation in this species. Gonadotropin releasing hormones (GnRh) were used in combination with dopamine receptor antagonists. Human chorionic gonadotropin (HCG) was administered in conjunction with catfish pituitary gonadotropin. Both sexes were successfully stripped and the eggs were inseminated artificially. Tigerfish eggs are small (0.65 mm diameter), demersal and slightly adhesive. Hatching occurs 22 h 30 min after insemination and free embryos are pelagic and display continuous vertical movement for a period of three days. Embryonic development was photographed until first feeding, 5 days after hatching. From these results as well as field observations, it is concluded that tigerfish spawns on a sandy substrate in the vicinity of aquatic vegetation.     

Evaluation of astigmatid mites as factitious food for rearing four predaceous phytoseiid mites (Acari: Astigmatina; Phytoseiidae)

Phytoseiids are possibly the most important mites used in biological control and are usually produced using a tritrophic system that, although efficient, is expensive and laborious. Mites of the cohort Astigmatina (Sarcoptiformes) have been used as factitious prey in the mass rearing of phytoseiids and may allow a much simpler production system. This research evaluated the potential of ten Astigmatina species to serve as factitious food sources for Euseius concordis (Chant), Iphiseiodes zuluagai Denmark and Muma, Neoseiulus barkeri Hughes and Neoseiulus californicus McGregor, all phytoseiid species commonly found in different countries. The high fecundity and survival rates obtained suggest that Thyreophagus n. sp. is a suitable prey for rearing N. barkeri and that Austroglycyphagus lukoschusi (Fain) and Blomia tropicalis is suitable for rearing N. californicus. Oviposition by E. concordis was negligible, but survivorship was high on most prey species, suggesting that these species may be useful for maintenance of the predator. I. zuluagai had low fecundity and survival on all the astigmatid species evaluated and none were suitable for its rearing.     

Rearing of silkworm larva in a closed gas revitalizing plant system

Plant growing and insect breeding experiments in the CICS (Closed Integrative Cultivating System) were carried out. The CICS was established for collecting experimental data to investigate gas circulation and mass exchange between plants and animals as well as animal growth and nutrient compositions in the Bioregenerative Life Support System. The CICS was 1.4 m high with the base measuring 1.4 m × 0.8 m. In the plant chamber, stem lettuce plants were grown in a staggered manner. Silkworms in five different instars were fed in the animal chamber. Every 4 days, the silkworms that had been in the 5th instar for 3 days and all the silkworm’ excreta were taken out of the system. Meanwhile, the silkworms in the first instar were transferred into the animal chamber. During this process, O₂ and CO₂ concentrations in the CICS were measured, and the growth and nutrient composition of the silkworms in the system were compared with those of silkworms reared in the open environment. Results showed that O₂ and CO₂ concentrations in the system were 19.07-20.61% and 0.11-0.35%, respectively. The comparison of growing differences between the silkworms fed in the animal chamber and those in the open environment indicates the insect's biomass increasing rates and bioconversion rates in the CICS were lower than those in the open environment, and the amounts of excreta produced in the animal chamber were larger. Protein content of the SP (Silkworm Powder) produced in the CICS was more than that in the open environment, while fat content of the SP in the CICS was lower than that in the open environment. Calcium, phosphorus and iron contents of the SP produced in the CICS were 139.00 mg calcium/100 g SP, 1.20 mg phosphorous/100 g SP, and 7.95 mg iron/100 g SP. In terms of amino acids, the quality of the SP produced in the CICS was equivalent to that gained in the open environment.     

Rearing success of a polyphagous predatorGeocoris ochropterus (Hem.: Lygaeidae) on preserved ant pupae ofOecophylla smaragdina

Some of the life-parameters such as nymphal development periods, growth (by weight), food consumption, egg laying period, rate, percent mortality ofGeocoris ochropterus (Fieber) have been studied on ant pupae (Oecophylla smaragdina Fabr.), a potential food available both naturally and commercially. The moisture and basic nutrients including protein, carbohydrate and lipid of the cold-preserved ant pupae have been determined to provide understanding of the dietary value of the food for mass rearing. Experiment with variable male company showed that total fecundity exceeds by a narrow margin in constant male company over fortnightly mating programme. No mating leads to reduction of egg laying in virgins.     

Nitrogen enrichment of host plants has mostly beneficial effects on the life-history traits of nettle-feeding butterflies

Butterflies rank among the most threatened animal groups throughout Europe. However, current population trends differ among species. The nettle-feeding butterflies Aglais io and Aglais urticae cope successfully with the anthropogenic land-use change. Both species are assumed to be pre-adapted to higher nitrogen contents in their host plant, stinging nettle (Urtica dioica). However, it is currently unknown, whether this pre-adaptation enables both Aglais species to cope successfully or even to benefit from the excessive nitrogen availabilities in nettles growing in modern farmlands. For this reason, this study focused on the response of both Aglais species to unfertilized nettles compared to nettles receiving 150 or 300 kg N ha⁻¹ yr⁻¹ (i.e., common fertilizer quantities of modern-day agriculture). Fertilized nettles were characterized by higher nitrogen concentrations and lower C:N ratios compared to the control group. In both Aglais species, the individuals feeding on fertilized nettles had higher survival rates, shorter larval periods and heavier pupae and, in A. urticae also longer forewings. All these trait shifts are beneficial for the individuals, lowering their risk to die before reproduction and increasing their reproductive potential. These responses agree with the well-accepted nitrogen-limitation hypothesis predicting a positive relationship between the nitrogen content of the diet and the performance of herbivorous insects. Furthermore, our findings suggest that the increasing abundance of both Aglais species may result not only from the increasing spread of nettles into the farmland but also from changes in their quality due to the eutrophication of the landscape during recent decades.     

The physical factor inducing spawning of the Biwa catfish, Silurus biwaensis

The physical factor inducing spawning of the Biwa catfish, Silurus biwaensis (Siluriformes: Siluridae), an endemic species of Lake Biwa, was investigated on the basis of field observations on 150 nights at the spawning site, the rocky shore of the Seta River, the lake's outlet, and environmental data from April to July in 1989–1994. The catfish gathered at the spawning site when the water level of the river rapidly rose and the rocky shoal became submerged, within a wide range of water temperature (15.0°–30.0°C); their spawning was induced in relation to increases in the submerged portion of the rocky shoal. This observation suggests that water level control operations in Lake Biwa might critically affect the spawning of this and other fish species. Received: December 17, 1999 / Revised: September 13, 2000 / Accepted: January 16, 2001     

Reproduction and early life history of northern squawfish,Ptychocheilus oregonensis,in Idaho's St. Joe River

Synopsis Reproduction and early life history of northern squawfish,Ptychocheilus oregonensis, was investigated in Idaho's St. Joe River from 1980–1981. Spawning occurs in large aggregations which mill near the substrate to broadcast eggs and milt. Males greatly outnumber females in the aggregations. Males mature at smaller sizes and younger ages, and exhibit slower growth and greater mortality than females, although females devote more resources than males to gonadal production. Spawning was observed in June and July at temperatures of 12 to 18° C and was restricted to sites with the unique combination of a gravel-cobble substrate free of sand and a bottom velocity of 0.4 m s^–1 or less. Juvenile northern squawfish schooled with other young cyprinids in sandy, zero-velocity, shallow-water margins of the river. Age 1 northern squawfish used deeper and more diverse microhabitats than juveniles. Growth of juveniles was rapid and variable during the first summer. During winter, average length did not increase and condition declined. Young northern squawfish ate a wide variety of crustaceans, aquatic insects, and terrestrial insects although individual fish tended to focus on one or two items. Diet breadth and food volume increased with age except in winter.     

Benefits and limitations of factitious prey and artificial diets on life parameters of predatory beetles,bugs, and lacewings: a mini-review

The primary peer-reviewed literature pertaining to rearing of predatory beetles, true bugs, and lacewings was reviewed and synthesized. This study focused on the literature published from 1998 to 2007. Advances in rearing were revealed in relation to the influence of factitious prey and artificial diets on predator life parameters. Eggs of the Angoumois grain moth and Mediterranean flour moth were factitious prey that supported the development and reproduction of many species in lieu of natural prey. Artificial diets based on vertebrate protein were generally inferior to factitious prey for production of predators. A few exceptional cases demonstrated potential for continuous rearing of true bugs and lacewings on artificial diet, as a stand-alone food source. Factors that could ensure progressive rearing success might involve (1) exploiting the highly polyphagous nature of certain species, (2) exposing predators to artificial diet for multiple generations to incite adaptation, (3) formulating artificial diets to match the texture and chemical composition of preferred natural prey, and (4) encasing the diet within Parafilm^® to resemble the shape of natural prey. Encasement may also reduce desiccation and retard spoilage of the diet. Identification of other factitious prey and development of artificial diets that ensure production of predators of high quality should be possible. This review was conducted, for the most part, in support of generalist insect predators used, or having the potential to be used, in augmentative biological control of pests on plants in semi-closed systems, such as greenhouses and interiorscapes.     

Sting frequency and progeny production of lab-cultured Cotesia marginiventris

A laboratory experiment was conducted to determine the impact of sting frequency on progeny production of Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae), a solitary, koinobiont endoparasitoid of noctuid pests. In replicated trials, young, mated, host-deprived C. marginiventris females were exposed to three Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) early instar larvae, one at a time, in Petri dish arenas, and observed as they stung these hosts once, twice, or thrice. The average amount of time that elapsed between stinging a host ranged from a minimum of 3 min, when females were exposed to unstung hosts, to a maximum of 8–11 min when females were exposed to previously stung hosts. Sting frequency had no effect on the yield of C. marginiventris progeny; approximately 90% of hosts, in all treatment groups, yielded a parasitoid mature larva, which spun a cocoon. No hosts yielded more than one parasitoid. The percentage of adult female progeny tended to increase with sting frequency; hosts that were stung thrice yielded 60% female C. marginiventris adults. The production of female progeny may depend on the egg allocation pattern of C. marginiventris females as well as the competitive interactions between siblings developing inside a shared host. This study suggests that S. exigua larvae can sustain 2–3 stings without diminishing their ability to yield a C. marginiventris mature larva. Provisioning enclosures with enough hosts to exceed the daily (per capita) oviposition rate of C. marginiventris females might limit the repeated stinging of the same hosts.